lst-0011-book.cpp
// https://godbolt.org/z/E9hcWGMW4
#include <regex>
#include <string>
#include <iostream>
using std::regex; using std::regex_match; using std::regex_search;
int main() {
std::cout << std::boolalpha;
regex pattern {"ello"};
std::string text = "Hello world";
auto b1 = regex_match (text.cbegin(), text.cend(), pattern); // does’t match
std::cout << b1 << "\n"; // Output: false
auto b2 = regex_search(text.cbegin(), text.cend(), pattern); // found
std::cout << b2 << "\n"; // Output: true
}